Collect. Czech. Chem. Commun. 2002, 67, 1223-1235

Covalent Analogues of DNA Base-Pairs and Triplets IV. Synthesis of Trisubstituted Benzenes Bearing Purine and/or Pyrimidine Rings by Cyclotrimerization of 6-Ethynylpurines and/or 5-Ethynyl-1,3-dimethyluracil

Michal Hoceka,*, Irena G. Staráa, Ivo Starýa and Hana Dvořákováb

a Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ-16610 Prague 6, Czech Republic
b Central Laboratory of NMR, Institute of Chemical Technology, Prague, CZ-16628 Prague 6, Czech Republic


Ni-Catalyzed cyclotrimerizations of 6-ethynylpurines 3 or 5-ethynyl-1,3-dimethyluracil (4) afforded the 1,2,4-tris(purin-6-yl)benzenes 7 or 1,2,4-tris(1,3-dimetyhyluracil-5-yl)benzene (9), respectively. The symmetrical 1,3,5-tris(purin-6-yl)benzenes 8 were also formed as minor products in very low yields. Co-cyclotrimerization of 9-benzyl-6-ethynylpurine (3a) with 4 afforded the tris(purinyl)benzene 7a as a major product along with 1,2-bis(9-benzylpurin-6-yl)-4-(1,3-dimethyluracil-5-yl)benzene (10) and a complex mixture of other derivatives and isomers. Compounds 7-10 are analogues of Hoogsteen base-triplets.

Keywords: Purines; Pyrimidines; Nucleobases; Hoogsteen triplets; Cyclotrimerizations; Nickel; Alkynes; [2+2+2] Cycloadditions.

References: 39 live references.